I just stumbled upon Korea operator LG Telecom's HomeZone service, which is an FMS pitch offering cheap in-home calls.
"Home Zone Service: a mobile phone in home phone’s disguise Subscribe to Home Zone Service and you would not need traditional fixed-line phone service ever again. Home Zone Service offers the convineince of mobile phones at a rate comparable to fixed-line service, at home or in your office.
Home Zone Service combines the benefits of the convenience of mobile phones with the thriftiness of fixed-line service in a single mobile handset. Home Zone Service is as easy as installing Access Point, the Home Zone Service device, in a place of choice. Whenever Home Zone Service subscriber makes a call within 30m from the Access Point, the call automatically registers at a rate comparable to fixed-line service. Up to seven mobile handsets can be operated via a single Access Point."
What's not clear to me is exactly how this works. I haven't been able to find much via Google, and unfortunately I don't speak Korean, so I have no way to interpret the FAQ on the more-detailed domestic part of LG's website.
There's a mysterious access-point widget with a 30m range that plugs into a power socket.... but which doesn't seem to have any hookup to a fixed broadband line that you'd need for either WiFi or a femtocell. I'm guessing that it's either some sort of repeater that signals to the network to flip to a lower tariff when it's in use, or perhaps it's got a CDMA modem in plus a Bluetooth antenna with cordless telephony profile (CTP). It needs a dedicated phone (there's a range of 6 according to the website)
Anyone able to shed any light?